J/ApJ/953/104 YSOs from Spitzer & Herschel surveys in LMC (Kokusho+, 2023)
Properties of star formation of the Large Magellanic Cloud as probed by young
stellar objects.
Kokusho T., Torii H., Kaneda H., Fukui Y., Tachihara K.
<Astrophys. J., 953, 104 (2023)>
=2023ApJ...953..104K 2023ApJ...953..104K
ADC_Keywords: Magellanic Clouds; YSOs; Stars, masses; Energy distributions;
Extinction; Infrared sources; Optical; Surveys;
Interstellar medium
Keywords: Large Magellanic Cloud ; Young stellar objects ; Star formation
Abstract:
We perform a systematic study of the evolutionary stages and stellar
masses of young stellar objects (YSOs) in the Large Magellanic Cloud
(LMC) to investigate the properties of star formation in the galaxy.
There are 4825 sources in our YSO sample, which are constructed by
combining the previous studies identifying YSOs in the LMC. Spectral
energy distributions of the YSOs from optical to infrared wavelengths
were fitted with a model consisting of stellar, polycyclic aromatic
hydrocarbon, and dust emissions. We utilize the stellar-to-dust
luminosity ratios thus derived to study the evolutionary stages of the
sources; younger YSOs are expected to show lower stellar-to-dust
luminosity ratios. We find that most of the YSOs are associated with
the interstellar gas across the galaxy, which are younger with more
gas, suggesting that more recent star formation is associated with
larger amounts of the interstellar medium (ISM). N157 shows a hint of
higher stellar-to-dust luminosity ratios between active star-forming
regions in the LMC, suggesting that recent star formation in N157 is
possibly in later evolutionary stages. We also find that the stellar
mass function tends to be bottom-heavy in supergiant shells (SGSs),
indicating that gas compression by SGSs may be ineffective in
compressing the ISM enough to trigger massive star formation. There is
no significant difference in the stellar mass function between YSOs
likely associated with the interface between colliding SGSs and those
with a single SGS, suggesting that gas compression by collisions
between SGSs may also be ineffective for massive star formation.
Description:
We combined the catalogs by Whitney+ (2008, J/AJ/136/18) and
Gruendl & Chu (2009, J/ApJS/184/172) to cover the entire LMC, using a
matching distance of 1". As a result, the combined catalog includes
2199 YSOs. We combined this Spitzer catalog with the Herschel YSO
catalog from Seale+ 2014, J/AJ/148/124. In total, there are
4825 sources in the YSO sample used in our study.
The near-IR point-source catalog of the LMC was produced by
Kato+ 2007 (II/288) who measured the J-, H-, and K-band magnitudes of
the LMC point sources with the InfraRed Survey Facility (IRSF). In the
optical wavelength, Zaritsky+ (2004, J/AJ/128/1606) established the
point-source catalog in the U, B, V, and I bands from the Magellanic
Clouds Photometric Survey (MCPS).
The SED fits were accepted with a confidence level of 95% for 4097 YSOs.
Some of our sample YSOs lack photometry by Spitzer. Hence we
performed photometry of such YSOs, using the Spitzer 3.6, 4.5, 5.6,
8.0, and 24um band images published by the SAGE team
(Meixner+ 2006AJ....132.2268M 2006AJ....132.2268M). We also performed aperture photometry
for some sources, using the near-IR maps observed by IRSF
(http://jvo.nao.ac.jp/portal/irsf.do).
See Section 2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 122 4097 Parameters for well-fitted YSOs
table2.dat 52 16 Parameters for of the supergiant shells
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See also:
II/288 : IRSF Magellanic Clouds Point Source Catalog (Kato+ 2007)
VII/232 : Nebulae in the Magellanic Clouds (Davies+ 1976)
J/A+AS/139/277 : LMC X-ray sources ROSAT PSPC catalogue (Haberl+, 1999)
J/AJ/128/1606 : Magellanic Clouds Photometric Survey: LMC (Zaritsky+, 2004)
J/AJ/132/2653 : JHKs photometry of N11 young stellar objects (Hatano+, 2006)
J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006)
J/ApJ/678/200 : YSOs in N63 and N180 (Caulet+, 2008)
J/AJ/136/18 : LMC SAGE. New candidate YSOs (Whitney+, 2008)
J/AJ/138/1003 : IR photometry of massive LMC stars (Bonanos+, 2009)
J/ApJ/695/511 : Young massive stars in LHA 120-N 44 (Chen+, 2009)
J/ApJS/184/172 : High- and intermediate-mass YSOs in the LMC (Gruendl+, 2009)
J/ApJ/699/150 : Spectral classif. of Massive YSOs in LMC (Seale+, 2009)
J/ApJ/721/357 : YSOs in the LMC star-forming region N206 (Romita+, 2010)
J/A+A/542/A66 : YSOs in 9 LMC star forming regions (Carlson+, 2012)
J/AJ/146/62 : HERschel HERITAGE in Magellanic Clouds (Meixner+, 2013)
J/AJ/148/124 : Herschel key program Heritage (Seale+, 2014)
J/ApJ/811/145 : LMC & SMC evolved stars with Herschel (Jones+, 2015)
J/MNRAS/470/3250 : SAGE LMC point-sources classification (Jones+, 2017)
J/A+A/624/A137 : Stellar models and isochrones (Haemmerle+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.5 deg RAdeg [68.7/91] Right Ascension (J2000)
10- 19 F10.6 deg DEdeg [-72.4/-65.2] Declination (J2000)
21- 25 F5.2 [Lsun] logLs [-0.15/7.2] Log, SED-derived stellar
luminosity
27- 30 F4.2 [Lsun] e_logLs [0.05/3.3] Uncertainty in logLs
32 A1 --- SED [a] a: Model SED is not consistent with the
V-band limiting magnitude (1)
34- 37 F4.2 [Lsun] logLdust [1.19/8.5] Log, SED-derived dust luminosity
39- 44 F6.2 [Lsun] e_logLdust [0.04/188] Uncertainty in logLdust
46- 50 F5.2 [Lsun] logLhot [-0.8/4.5]? Log, SED-derived hot dust
luminosity
52- 57 F6.2 [Lsun] e_logLhot [0.04/116]? Uncertainty in logLhot
59- 63 F5.2 [Lsun] logLwarm [-0.12/8.5]? Log, SED-derived warm dust
luminosity
65- 71 F7.2 [Lsun] e_logLwarm [0.06/1406]? Uncertainty in logwarm
73- 76 F4.2 [Lsun] logLcold [1/5.1]? Log, SED-derived cold dust
luminosity
78- 81 F4.2 [Lsun] e_logLcold [0.09/2.6]? Uncertainty in logcold
83- 87 F5.2 [Lsun] logLpah [-1.4/4.1]? Log, SED-derived PAH luminosity
89- 93 F5.2 [Lsun] e_logLpah [0.06/22]? Uncertainty in logpah
95- 99 F5.2 [Msun] logMs [-0.12/2]? Log, derived stellar mass (2)
101- 104 F4.2 [Msun] e_logMs [0.01/1.1]? Uncertainty in logMs
106- 110 F5.1 mag Av [0/105] Dervied V-band extinction
112- 116 F5.1 mag e_Av [0/154] Uncertainty in Av
118- 122 A5 --- Ref Reference (s) (3)
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Note (1): Model SED is not consistent with the V band limiting
magnitude from Zaritsky+ 2004, J/AJ/128/1606
Note (2): logMs is estimated for YSOs which have Mstar in the mass
range 0.7-120Msun
Note (3): References as follows:
1 = Whitney et al. 2008, J/AJ/136/18
(<SSTISAGE1C JHHMMSS.ss+DDMMSS.s> in Simbad)
2 = Gruendl & Chu 2009, J/ApJS/184/172
(<[GC2009] JHHMMSS.ss+DDMMSS.s> in Simbad)
3 = Seale et al. 2014, J/AJ/148/124
( for Simbad)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Name Original Name (1)
7- 8 I2 h RAh [4/5] Hour of Right Ascension (J2000)
10- 11 I2 min RAm Minute of Right Ascension (J2000)
13- 14 I2 s RAs Second of Right Ascension (J2000)
16- 16 A1 --- DE- [-] Sign of the Declination (J2000)
17- 18 I2 deg DEd [65/70] Degree of Declination (J2000)
20- 21 I2 arcmin DEm Arcminute of Declination (J2000)
23- 24 I2 arcsec DEs Arcsecond of Declination (J2000)
26- 29 F4.1 arcmin amaj [14.7/56.6] Shell radius, major axis
31- 34 F4.1 arcmin bmin [14.7/59] Shell radius, minor axis
36- 37 I2 deg PA [0/90] Position angle of Shell, east of north
39- 41 I3 --- NYSO [11/307] Number of YSOs present within Shell
43- 47 F5.2 --- R [-0.62/0.12] Correlation coefficient (2)
49- 52 F4.2 --- p [0.03/1] Calculated p value (2)
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Note (1): Original name from Kim+ 1999AJ....118.2797K 1999AJ....118.2797K
(<[KDS99] SGS NN> in Simbad).
Note (2): Correlation coefficients together with their p calculated
for the relations between Lstar/Ldust and the distances from
the center for the YSOs present inside the shell.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 17-Sep-2025